The purpose of this technical committee report is to present the results of an investigation of the effects of chemical water treatment on single-face mechanical seals in recirculating hot water systems. The study was done following the publication in 1970 of NACE Publication 7A170, "Causes of Failure of Rotary Shaft Seals in Cooling and Heating System Pumps." That report was published by Unit Committee T-7A on Cooling Water after that committee had conducted a symposium on the subject, held various panel discussions, reviewed literature, and investigated numerous case histories. Conclusions reported by the committee suggested that the following appeared to be major causes for premature failure of single-face mechanical seals in water pumps not equipped with seal chambers: - Improper installation of seal or pump - Operating dry or partially dry - Suspended solids in circulating water - Excessively high water temperature